论文标题
CA（CO，ir）2AS2晶体中的铁磁群集玻璃相
Ferromagnetic cluster-glass phase in Ca(Co,Ir)2As2 crystals
论文作者
论文摘要
CA [Co_（2-X）IR_（X）] _（2-Y）AS2的单晶具有0 <= x <= 0.35和0.10 <= y <= 0.14，已使用自升力技术生长，并以单晶体X射线X射线衍射（XRD），能量脱离X射线射线和竞争量的X射线和磁力仪的温度，并以单晶体X射线差异（XRD）为特征。时间t和热容量CP（H，T）测量。 XRD的改进表明，所有IR取代的晶体都在折叠的四边形结构中结晶，而父caco_（2-y）AS2化合物也是如此。 CACO_（1.86）AS2中CO的3.3％IR取代大大降低了A型抗铁磁（AFM）过渡温度从52 K到23 K，并显着增强了Sommerfeld Electronic Electonic Heatociality的能力。从Curie-Weiss拟合到CHI（T> TN）数据获得的阳性Weiss温度表明，所有X的主要磁相互作用都是铁磁相互作用（FM）。推断出磁相边界存在于x = 0.14和x = 0.17之间，从x依赖性的X依赖性和curie-weiss拟合中的weiss温度中的不连续性存在。 CHI（T）数据也揭示了随着X的增加而大大增加的FM波动。 X> = 0.17的磁接地状态是一种自旋玻璃，如在场冷却和零视野冷却测量之间的CHI（T）中所示，以及来自M小场中M在表现出拉伸指数时间依赖性的小场中的松弛。自旋玻璃对订购的FM组件很小，因此推断为由小的FM簇组成。 x = 0.14的cp在低t上的对数t依赖性与存在明显的FM量子波动一致。该组合物在x = 0.16的t = 0边界接近a型AFM相之间的X = 0.16，其中包含旋转的铁磁层和FM群集玻璃相。
Single crystals of Ca[Co_(2-x)Ir_(x)]_(2-y)As2 with 0 <= x <= 0.35 and 0.10 <= y <= 0.14 have been grown using the self-flux technique and characterized by single-crystal x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy, magnetization M and magnetic susceptibility chi measurements versus temperature T, magnetic field H, and time t, and heat capacity Cp(H,T) measurements. The XRD refinements reveal that all the Ir-substituted crystals crystallize in a collapsed-tetragonal structure as does the parent CaCo_(2-y)As2 compound. A small 3.3% Ir substitution for Co in CaCo_(1.86)As2 drastically lowers the A-type antiferromagnetic (AFM) transition temperature TN from 52 to 23 K with a significant enhancement of the Sommerfeld electronic heat-capacity coefficient. The positive Weiss temperatures obtained from Curie-Weiss fits to the chi(T>TN) data indicate that the dominant magnetic interactions are ferromagnetic (FM) for all x. A magnetic phase boundary is inferred to be present between x = 0.14 and x = 0.17 from a discontinuity in the x dependences of the effective moment and Weiss temperature in the Curie-Weiss fits. FM fluctuations that strongly increase with increasing x are also revealed from the chi(T) data. The magnetic ground state for x >= 0.17 is a spin glass as indicated by hysteresis in chi(T) between field-cooling and zero-field-cooling measurements and from the relaxation of M in a small field that exhibits a stretched-exponential time dependence. The spin glass has a small FM component to the ordering and is hence inferred to be comprised of small FM clusters. A logarithmic T dependence of Cp at low T for x = 0.14 is consistent with the presence of significant FM quantum fluctuations. This composition is near the T = 0 boundary at x = 0.16 between the A-type AFM phase containing ferromagnetically-aligned layers of spins and the FM cluster-glass phase.
